Proceedings of the Sixty-first Annual Meeting of the Northeastern ...
Proceedings of the Sixty-first Annual Meeting of the Northeastern ... Proceedings of the Sixty-first Annual Meeting of the Northeastern ...
110 PUMPKIN RESPONSE TO HALOSUFSULFURON, FOMESAFEN, AND TERBACIL. R.B. Batts, North Caroline State Univ., Raleigh, A.W. MacRae, University of Georgia, Tifton, and J.B. Beam, North Carolina Cooperative Ext. Service, Lincolnton. ABSTRACT Pumpkin trials were conducted in Iron Station and Edenton, NC and Blairsville, GA in 2006 to determine crop tolerance and yield response of ‘Magic Lantern’ and ‘Appalachian’ pumpkin to halosulfuron (Sandea 75 DF), fomesafen (Reflex 2 SC) and terbacil (Sinbar 80 WP). Sandea was applied preemergence (PRE), postemergence (POST) or post-directed (P-DIR) at 0.5, 0.75, or 1.0 oz/A. Reflex and Sinbar was applied PRE at 1 or 2 pt/A and 3 or 6 oz/A, respectively. For comparison purposes, a hand-weeded control was included. Injury data were combined across cultivars at all locations and across both North Carolina sites. Compared to the hand-weeded control, Sandea applied PRE, POST, and P-DIR injured pumpkin 37-51, 33-37, and 18-20%, respectively, in North Carolina 2 wks after treatment (WAT). In contrast, injury seen in Georgia ranged from 5-7%, 19- 32%, and 0% when applied PRE, POST, and P-DIR, respectively. Optimum growing conditions were prevalent in Georgia for the duration of the growing season, limiting injury from herbicide application. Similar results were observed with Reflex and Sinbar applications in North Carolina causing 26-56 and 84-98% injury, respectively, while in Georgia these applications only caused 4-13 and 16-65% injury. Severe injury from Sinbar applications resulted in a reduction in pumpkin stand. Sandea P-DIR had the least amount of injury at all locations, while the PRE timing was most injurious in North Carolina and POST was most injurious in Georgia. PRE injury was expressed as crop stunting, while POST and P-DIR injury appeared as discoloration in the terminals of the plants. As with injury, yield data were combined across cultivar at all sites and across both North Carolina locations. When compared to the hand-weeded control in North Carolina, yield reduction (total weight) from Sandea treatments ranged from 10 to 25% with no trend for rate or timing of application. Yield reduction from the high rate of Reflex and both rates of Sinbar were greater than any other treatment in North Carolina. Similarly, these three were the only treatments to have greater plant stand reduction compared to the nontreated control. In Georgia, the two Sinbar treatments were the only treatments with reduction in yield compared to the nontreated control. The only reduction in plant stand was with the high rate of Sinbar. Based on these data, Sandea appears to be relatively safe to pumpkins, especially in heavy weed situations where some injury is acceptable. However, Sinbar appears to be too injurious, especially if heavy or excessive rainfall follows a PRE application. 92
111 ASSESSMENT OF THE COMBINED EFFECTS OF MESOTRIONE AND HEXAZINONE ON WEEDS IN WILD MAINE BLUEBERRIES. D.E. Yarborough and K.F.L. Guiseppe, University of Maine, Orono. ABSTRACT Hexazinone has been the principle herbicide used in Maine wild blueberry (Vaccinium angustifolium) fields for over twenty years. There is evidence that reliance on hexazinone without other alternative herbicides has resulted in increased populations of grasses and other herbaceous weeds. There is a need for herbicides with different modes of action for herbicide rotations in wild blueberry fields. In order to evaluate the herbicide mesotrione with and without hexazinone a split block design was established on six wild blueberry fields throughout the state to obtain a diversity of soil types and weed species. A block was established in the Maine towns of Union, Belfast, Penobscot, Orland, Township 19 and at the Blueberry Hill Experimental Farm in Jonesboro. A 16 x 20 m block was comprised of 4 x 16 m treatment plots including an untreated control, mesotrione at 444 ml/ha preemergence, 222 ml/ha preemergence and 222 ml/ha postemergence on the same plot, and 222 ml/ha postemergence. At right angles on an 8 x 20 m plot of either an untreated control or a hexazinone treatment at 1 kg/ha was applied to give a total of eight combinations. Pre-emergence treatments were sprayed on 8-11 May. Postemergence treatments were sprayed on 6-9 June. Treatment effects were assessed for broadleaf, fern and grass weed cover using a Daubenmire cover scale and wild blueberry phytotoxicity as percent injury from four 1m square subplots within each treatment. The first weed cover evaluation was on June 19 and 23 and the second was on August 14 and 23, 2006. Grass cover (Figure 1) was highest in the control, postemergence at 222 ml/ha and preemergence at 444 ml/ha treatments for both evaluations. Hexazinone combined with the 222 ml/ha postemergence or 3 oz/a pre and 3 oz/a postemergence mesotrione had the best control of grass cover in both evaluations. The 222 ml/ha pre and postemergence mesotrione treatment without hexazinone on the second evaluation date was statistically the same as with hexazinone. Broadleaf weed cover (Figure 2) was highest in the untreated control and the 222 ml/ha preemergence mesotrione treatment. The combinations of hexazinone with mesotrione resulted in the lowest broadleaf cover ratings as did the 222 ml/ha pre and postemergence combination treatment. The mesotrione applications at the higher rate preemergence or at the low rate pre and post emergence gave equivalent control to the hexazinone application. When these applications were combined with hexazinone additional suppression of both grasses and broadleaf weeds was obtained. 93
- Page 60 and 61: 60 THE EFFICACY AND CROP TOLERANCE
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111<br />
ASSESSMENT OF THE COMBINED EFFECTS OF MESOTRIONE AND<br />
HEXAZINONE ON WEEDS IN WILD MAINE BLUEBERRIES. D.E. Yarborough and<br />
K.F.L. Guiseppe, University <strong>of</strong> Maine, Orono.<br />
ABSTRACT<br />
Hexazinone has been <strong>the</strong> principle herbicide used in Maine wild blueberry<br />
(Vaccinium angustifolium) fields for over twenty years. There is evidence that reliance<br />
on hexazinone without o<strong>the</strong>r alternative herbicides has resulted in increased<br />
populations <strong>of</strong> grasses and o<strong>the</strong>r herbaceous weeds. There is a need for herbicides<br />
with different modes <strong>of</strong> action for herbicide rotations in wild blueberry fields. In order to<br />
evaluate <strong>the</strong> herbicide mesotrione with and without hexazinone a split block design was<br />
established on six wild blueberry fields throughout <strong>the</strong> state to obtain a diversity <strong>of</strong> soil<br />
types and weed species. A block was established in <strong>the</strong> Maine towns <strong>of</strong> Union, Belfast,<br />
Penobscot, Orland, Township 19 and at <strong>the</strong> Blueberry Hill Experimental Farm in<br />
Jonesboro. A 16 x 20 m block was comprised <strong>of</strong> 4 x 16 m treatment plots including an<br />
untreated control, mesotrione at 444 ml/ha preemergence, 222 ml/ha preemergence<br />
and 222 ml/ha postemergence on <strong>the</strong> same plot, and 222 ml/ha postemergence. At<br />
right angles on an 8 x 20 m plot <strong>of</strong> ei<strong>the</strong>r an untreated control or a hexazinone treatment<br />
at 1 kg/ha was applied to give a total <strong>of</strong> eight combinations. Pre-emergence treatments<br />
were sprayed on 8-11 May. Postemergence treatments were sprayed on 6-9 June.<br />
Treatment effects were assessed for broadleaf, fern and grass weed cover using a<br />
Daubenmire cover scale and wild blueberry phytotoxicity as percent injury from four 1m<br />
square subplots within each treatment. The <strong>first</strong> weed cover evaluation was on June 19<br />
and 23 and <strong>the</strong> second was on August 14 and 23, 2006. Grass cover (Figure 1) was<br />
highest in <strong>the</strong> control, postemergence at 222 ml/ha and preemergence at 444 ml/ha<br />
treatments for both evaluations. Hexazinone combined with <strong>the</strong> 222 ml/ha<br />
postemergence or 3 oz/a pre and 3 oz/a postemergence mesotrione had <strong>the</strong> best<br />
control <strong>of</strong> grass cover in both evaluations. The 222 ml/ha pre and postemergence<br />
mesotrione treatment without hexazinone on <strong>the</strong> second evaluation date was<br />
statistically <strong>the</strong> same as with hexazinone. Broadleaf weed cover (Figure 2) was highest<br />
in <strong>the</strong> untreated control and <strong>the</strong> 222 ml/ha preemergence mesotrione treatment. The<br />
combinations <strong>of</strong> hexazinone with mesotrione resulted in <strong>the</strong> lowest broadleaf cover<br />
ratings as did <strong>the</strong> 222 ml/ha pre and postemergence combination treatment. The<br />
mesotrione applications at <strong>the</strong> higher rate preemergence or at <strong>the</strong> low rate pre and post<br />
emergence gave equivalent control to <strong>the</strong> hexazinone application. When <strong>the</strong>se<br />
applications were combined with hexazinone additional suppression <strong>of</strong> both grasses<br />
and broadleaf weeds was obtained.<br />
93